How the Haswell Chip Makes the New MacBook Air Last 12 Hours

Half day. Photo: Alex WashburnWired

New chips should excite you. Instead, the news reports you read whenever some new microprocessor is released are the dullest things in the world. They are obtuse and inscrutable, a mish-mash of numbers and acronyms for technologies you can’t really wrap your head around.

But people do sit up and pay attention when something like the new MacBook Air is announced. Everyone gets very excited, citing Apple’s claims of new capabilities, better performance specs, and longer battery life. It turns out that new Air has one of Intel’s brand new Haswell chips inside, and that this new low-power processor is responsible for many of the MacBook Air’s performance gains. If it takes the introduction of a high-profile Apple product to make microchips sexy, so be it.

Intel’s U-series “Haswell” line of low-power, dual-core CPUs are destined for ultrabooks — hence the “U”. In fact, these chips are expressly designed to squeeze more computing cycles out of the ever-shrinking batteries inside our ever-thinning mobile computers. While the MacBook Air is already known to have better-than-average battery life (especially for a compact ultra-portable laptop), Apple says the new Haswell chips can keep the machines alive even longer. The company claims the new Haswell-powered Airs can achieve up to 12 hours of battery life on the 13-inch model, and up to nine hours on the 11-inch model. When you’re working on any laptop, the battery status indicator is always a source of frustration and anxiety, so these improvements are a very big deal for Apple’s svelte notebooks.

There’s more to the Haswell upgrade than just power savings — Apple also claims a modest performance boost to overall CPU speed, as well as a 40 percent speed boost to graphics processing.

But battery life is the biggie. Intel has said that the new chips will increase battery life by 50 percent during active loads when compared to Ivy Bridge chips, and that in standby mode, battery life should improve by up three times over Ivy Bridge chips. The MacBook Air comes very close to hitting those numbers, according to Apple, though specifics haven’t yet been determined. Apple says that during active loads, the 13-inch MacBook Air gets a 42 percent boost to battery life, while the 11-inch MacBook Air gets a 45 percent bump. Much of this battery magic was achieved by cramming a voltage regulator onto the chip. Intel calls its voltage-regulator-on-the-chip design a FIVR (“fully integrated voltage regulator”).

Another power-saving feature comes from Intel combining the chipset and CPU onto a single package. In previous generation chips, the CPU and chipset had different power requirements. If the U-series Sandy Bridge CPU was pulling 17 watts, and the chipset was pulling an additional 3 watts, the whole system was pulling 20 watts. By combining the CPU and chipset, Intel has been able to better control power usage: the entire Haswell U-series CPU and chipset pull only 15 watts.

On the graphics end, Intel’s Iris Graphics technology is supposed to offer twice the 3D performance for the U-series ultrabook chips and mid-level H-series chips. Just like the bump to battery life, the Air’s graphics boost falls just shy of Intel’s performance claims: around 40 percent. So while it’s not the biggest boost we’ll see on Haswell computers, it’s still a nice boost to the Air’s graphics capabilities.

One thing many Apple fans were hoping to see announced at WWDC is MacBook Air with a Retina display. But, Apple doesn’t seem ready to throw its high-density display onto the Macbook Air line. Those superfine screens suck power at much higher rates, and it’s doubtful that the efficiency gains from Haswell were dramatic enough to offset the battery hit a Retina display would cause were Apple to drop one into the Air line.

So while chip technology is some pretty deep math, the real-world performance boosts we’ll see on the MacBook Air — and other Haswell ultrabooks to follow — are something everyone can understand and appreciate.

One other note about how these improvements are rolled out. Haswell is the latest “tock” chip in Intel’s “Tick Tock” roadmap, the company’s two-step iteration cycle. Intel begins a new cycle by releasing a smaller version of the previous chip architecture where it shrinks the CPU’s design (a “tick”), then releases a different, newly engineered chip architecture (a “tock”). In this current “Tick Tock” cycle, the “tick” moved the Sandy Bridge CPU architecture to a smaller die size of 22nm, while the “tock” marked the introduction of the new Haswell microarchitecture. The next “tick,” due next year, will shrink the Haswell architecture from a 22nm die to a 14nm die.